During typical use of a computer, such as a personal computer, a variety of situations arise in which multiple items of information are presented to the user. For instance, the user may have several applications open, and each application typically has one or more containers to display content associated with the application. In many graphical user interfaces, such containers take the form of windows. The various items of information, i.e. the content of the respective windows, may be unrelated to one another. In other situations, the various items of information may have a structured relationship to one another. An example of this latter situation is a display of the contents of the computer's file system.
A computer's file system is responsible for managing the reading and writing of data on storage devices that are mounted on the computer, for example internal disk drives, network storage devices, and the like. In the case of personal computers and workstations, a graphical user interface might be used to view the structure of the file system, e.g. the hierarchy of objects such as directories, folders and files stored therein. Typically, the graphical user interface provides a plurality of alternative ways in which to view the contents of the file system. For example, one approach may comprise a hierarchical view, in which the nested relationship of files and folders to one another is displayed in the form of a tree structure. A browser can be associated with this type of view, in which the hierarchical view of folders and files is displayed in one pane of the browser window. When the user selects a folder in that pane, the contents of that folder are displayed in another pane of the window. Each pane represents a separate container of information.
In another approach, sometimes identified as an icon view, the files and folders at a particular level of the file system structure are displayed as individual icons within a window. If the user clicks upon a folder within that window, the contents of that folder are displayed. Depending on user preferences, the new information pertaining to the contents of the folder might replace the previous information within the existing window, or a new window might be displayed in an overlapping manner on top of the existing window.
A column view offers another approach for displaying the contents of a file system. An example of the column view is illustrated in FIGS. 1a-1f. FIG. 1a illustrates a window having columns, or panes, that constitute containers corresponding to respective levels of the file system. In the example of FIG. 1a, the left and middle columns display the objects at the two highest levels of the file system, respectively. The left column 10 identifies the available storage resources for the computer, in this case an internal hard disk drive 12, a removable compact disk 14, and a network 16. In this example, the user has clicked on the icon for the hard disk drive 12, and consequently the files and folders at the highest level of this storage medium are displayed in the middle column 18. Since the list of folders and files to be displayed in this column exceeds the height of the window, a vertical scroll bar 19 is displayed adjacent the column, to permit the user to view all of the objects on the hard disk drive.
If the user clicks on one of the folders in the second column 18, the display changes to that illustrated in FIG. 1b. In this view, a third column 20 on the right side of the window illustrates the contents of the folder that was selected, in this case the folder labeled “Documents.”
If the user clicks on one of the folders in the third column 20, the display changes to that illustrated in FIG. 1c. In this view, all of the prior columns have shifted to the left, and a fourth column 24 illustrates the contents of the folder on which the user clicked, in this case the folder labeled “Web Pages.” In this view, the first column 10 is no longer visible. If the user desires to view the first column, it is necessary to select a horizontal scroll bar 22 and move it to the left, so that the contents of the window shift to the right, which will result in the view of FIG. 1b. 
In a similar manner, if the user clicks on a folder in the fourth column 24, the display changes to that illustrated in FIG. 1d, in which a fifth column 26 that lists the contents of the selected file is displayed. FIG. 1e illustrates the results of clicking on a folder in the fifth column 26, which results in the display of a sixth column 28, that lists the contents of the “Graphics” folder in the fifth column. Finally, if the user clicks on one of the documents in the column 28, information about that document appears in another new column 29, as shown in FIG. 1f. It can be seen that, as each successive column is displayed, the scroll bar 22 becomes shorter, due to the fact that there are a greater number of columns over which the user can scroll the display.
It may be possible for the user to expand the size of the window, so that a greater number of columns might be viewed at once. However, there is a practical limit to the size of the window, and hence the number of columns that can be viewed simultaneously. As a result, if more than a few levels of the file system are to be accessed, not all of the columns can appear in the window together, and it becomes necessary for the user to scroll the displayed columns in order to view the contents of the various levels of the file system that are not adjacent one another.
As a result of the need to scroll the display in order to view separated columns, the user is unable to obtain an overview of the total path from the highest level in the file system to a folder or file of interest. Since the user is only presented with a view that is limited to a few adjacent levels of the file system at any one time, it is difficult to obtain the full context of the file system. For example, when viewing the fifth, sixth and seventh columns illustrated in FIG. 1f, the user may not remember whether he is looking at files stored on the hard drive or those stored on a removable disk.
The foregoing problem is not limited to file system viewers. In general, it can arise in the context of any set of information in which the various items of information have a structured relationship to one another, such as a hierarchical relationship, and it is desirable to view such relationship over an appreciable range of items. For instance, it can occur in an application which displays program code objects in the form of a hierarchy.